Dont go for interview if you can't join within 1 month. They will waste your time in taking interview in weekdays. Event after you clear all rounds of interview they will not give you offer if you can't join within month. this is happened with me and my many friends My question to their HR team is why you don't tell this before scheduling interview.

In total there are 3 rounds. 1 st being technical. 2nd being technical and managerial and 3rd being the HR round. The entire process till the release of offer letter took around a month for me.